Sidebar different widths on homepage/posts?

I just activated the Lugada theme and have been playing around with the column widths as I wanted the sidebar to be narrower and my content to be wider.

I have successfully changed them to my desired widths however I noticed that when I click onto a specific post my sidebar reverts back to the old size and as it then doesn’t fit next to my content is moved down to the bottom (and ends up looking as though it’s part of the footer). It only does this for posts, pages are still fine.

Can anyone tell me what coding I need to amend and what to change it to?